45
from bzrlib.hooks import HookPoint, Hooks
48
class LockHooks(Hooks):
52
self.create_hook(HookPoint('lock_acquired',
53
"Called with a bzrlib.lock.LockResult when a physical lock is "
54
"acquired.", (1, 8), None))
55
self.create_hook(HookPoint('lock_released',
56
"Called with a bzrlib.lock.LockResult when a physical lock is "
57
"released.", (1, 8), None))
61
"""Base class for locks.
63
:cvar hooks: Hook dictionary for operations on locks.
69
class LockResult(object):
70
"""Result of an operation on a lock; passed to a hook"""
72
def __init__(self, lock_url, details=None):
73
"""Create a lock result for lock with optional details about the lock."""
74
self.lock_url = lock_url
75
self.details = details
77
def __eq__(self, other):
78
return self.lock_url == other.lock_url and self.details == other.details
88
have_ctypes_win32 = False
89
if sys.platform == 'win32':
92
import win32con, win32file, pywintypes, winerror
99
have_ctypes_win32 = True
104
class _OSLock(object):
41
from bzrlib.errors import LockError
42
from bzrlib.osutils import realpath
43
from bzrlib.trace import mutter
46
class _base_Lock(object):
110
48
def _open(self, filename, filemode):
111
self.filename = osutils.realpath(filename)
113
self.f = open(self.filename, filemode)
50
self.f = open(filename, filemode)
115
52
except IOError, e:
116
if e.errno in (errno.EACCES, errno.EPERM):
117
raise errors.LockFailed(self.filename, str(e))
118
53
if e.errno != errno.ENOENT:
121
56
# maybe this is an old branch (before may 2005)
122
trace.mutter("trying to create missing lock %r", self.filename)
124
self.f = open(self.filename, 'wb+')
57
mutter("trying to create missing branch lock %r", filename)
59
self.f = open(filename, 'wb+')
128
"""Clear the self.f attribute cleanly."""
133
62
def __del__(self):
135
64
from warnings import warn
136
65
warn("lock on %r not released" % self.f)
140
69
raise NotImplementedError()
147
LOCK_SH = fcntl.LOCK_SH
148
LOCK_NB = fcntl.LOCK_NB
149
lock_EX = fcntl.LOCK_EX
152
class _fcntl_FileLock(_OSLock):
72
############################################################
79
class _fcntl_FileLock(_base_Lock):
154
83
def _unlock(self):
155
84
fcntl.lockf(self.f, fcntl.LOCK_UN)
88
"""Clear the self.f attribute cleanly."""
159
93
class _fcntl_WriteLock(_fcntl_FileLock):
163
97
def __init__(self, filename):
164
super(_fcntl_WriteLock, self).__init__()
165
# Check we can grab a lock before we actually open the file.
166
self.filename = osutils.realpath(filename)
167
if self.filename in _fcntl_WriteLock._open_locks:
169
raise errors.LockContention(self.filename)
171
self._open(self.filename, 'rb+')
172
# reserve a slot for this lock - even if the lockf call fails,
173
# at thisi point unlock() will be called, because self.f is set.
174
# TODO: make this fully threadsafe, if we decide we care.
175
_fcntl_WriteLock._open_locks.add(self.filename)
98
# standard IO errors get exposed directly.
99
self._open(filename, 'wb')
177
# LOCK_NB will cause IOError to be raised if we can't grab a
179
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
101
self.filename = realpath(filename)
102
if self.filename in self.open_locks:
104
raise LockError("Lock already held.")
105
# reserve a slot for this lock - even if the lockf call fails,
106
# at thisi point unlock() will be called, because self.f is set.
107
# TODO: make this fully threadsafe, if we decide we care.
108
self.open_locks[self.filename] = self.filename
109
fcntl.lockf(self.f, fcntl.LOCK_EX)
180
110
except IOError, e:
181
if e.errno in (errno.EAGAIN, errno.EACCES):
182
# We couldn't grab the lock
184
111
# we should be more precise about whats a locking
185
112
# error and whats a random-other error
186
raise errors.LockContention(self.filename, e)
188
115
def unlock(self):
189
_fcntl_WriteLock._open_locks.remove(self.filename)
116
del self.open_locks[self.filename]
193
120
class _fcntl_ReadLock(_fcntl_FileLock):
197
122
def __init__(self, filename):
198
super(_fcntl_ReadLock, self).__init__()
199
self.filename = osutils.realpath(filename)
200
_fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
201
_fcntl_ReadLock._open_locks[self.filename] += 1
123
# standard IO errors get exposed directly.
202
124
self._open(filename, 'rb')
204
# LOCK_NB will cause IOError to be raised if we can't grab a
206
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
126
fcntl.lockf(self.f, fcntl.LOCK_SH)
207
127
except IOError, e:
208
128
# we should be more precise about whats a locking
209
129
# error and whats a random-other error
210
raise errors.LockContention(self.filename, e)
212
132
def unlock(self):
213
count = _fcntl_ReadLock._open_locks[self.filename]
215
del _fcntl_ReadLock._open_locks[self.filename]
217
_fcntl_ReadLock._open_locks[self.filename] = count - 1
220
def temporary_write_lock(self):
221
"""Try to grab a write lock on the file.
223
On platforms that support it, this will upgrade to a write lock
224
without unlocking the file.
225
Otherwise, this will release the read lock, and try to acquire a
228
:return: A token which can be used to switch back to a read lock.
230
if self.filename in _fcntl_WriteLock._open_locks:
231
raise AssertionError('file already locked: %r'
234
wlock = _fcntl_TemporaryWriteLock(self)
235
except errors.LockError:
236
# We didn't unlock, so we can just return 'self'
241
class _fcntl_TemporaryWriteLock(_OSLock):
242
"""A token used when grabbing a temporary_write_lock.
244
Call restore_read_lock() when you are done with the write lock.
247
def __init__(self, read_lock):
248
super(_fcntl_TemporaryWriteLock, self).__init__()
249
self._read_lock = read_lock
250
self.filename = read_lock.filename
252
count = _fcntl_ReadLock._open_locks[self.filename]
254
# Something else also has a read-lock, so we cannot grab a
256
raise errors.LockContention(self.filename)
258
if self.filename in _fcntl_WriteLock._open_locks:
259
raise AssertionError('file already locked: %r'
262
# See if we can open the file for writing. Another process might
263
# have a read lock. We don't use self._open() because we don't want
264
# to create the file if it exists. That would have already been
265
# done by _fcntl_ReadLock
267
new_f = open(self.filename, 'rb+')
269
if e.errno in (errno.EACCES, errno.EPERM):
270
raise errors.LockFailed(self.filename, str(e))
273
# LOCK_NB will cause IOError to be raised if we can't grab a
275
fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
277
# TODO: Raise a more specific error based on the type of error
278
raise errors.LockContention(self.filename, e)
279
_fcntl_WriteLock._open_locks.add(self.filename)
283
def restore_read_lock(self):
284
"""Restore the original ReadLock."""
285
# For fcntl, since we never released the read lock, just release the
286
# write lock, and return the original lock.
287
fcntl.lockf(self.f, fcntl.LOCK_UN)
289
_fcntl_WriteLock._open_locks.remove(self.filename)
290
# Avoid reference cycles
291
read_lock = self._read_lock
292
self._read_lock = None
296
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
299
if have_pywin32 and sys.platform == 'win32':
300
LOCK_SH = 0 # the default
301
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
302
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
305
class _w32c_FileLock(_OSLock):
307
def _lock(self, filename, openmode, lockmode):
308
self._open(filename, openmode)
310
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
311
overlapped = pywintypes.OVERLAPPED()
313
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
315
except pywintypes.error, e:
317
if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
318
raise errors.LockContention(filename)
319
## import pdb; pdb.set_trace()
323
raise errors.LockContention(filename, e)
326
overlapped = pywintypes.OVERLAPPED()
328
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
331
raise errors.LockContention(self.filename, e)
334
class _w32c_ReadLock(_w32c_FileLock):
335
def __init__(self, filename):
336
super(_w32c_ReadLock, self).__init__()
337
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
339
def temporary_write_lock(self):
340
"""Try to grab a write lock on the file.
342
On platforms that support it, this will upgrade to a write lock
343
without unlocking the file.
344
Otherwise, this will release the read lock, and try to acquire a
347
:return: A token which can be used to switch back to a read lock.
349
# I can't find a way to upgrade a read lock to a write lock without
350
# unlocking first. So here, we do just that.
353
wlock = _w32c_WriteLock(self.filename)
354
except errors.LockError:
355
return False, _w32c_ReadLock(self.filename)
359
class _w32c_WriteLock(_w32c_FileLock):
360
def __init__(self, filename):
361
super(_w32c_WriteLock, self).__init__()
362
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
364
def restore_read_lock(self):
365
"""Restore the original ReadLock."""
366
# For win32 we had to completely let go of the original lock, so we
367
# just unlock and create a new read lock.
369
return _w32c_ReadLock(self.filename)
372
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
375
if have_ctypes_win32:
376
# These constants were copied from the win32con.py module.
377
LOCKFILE_FAIL_IMMEDIATELY = 1
378
LOCKFILE_EXCLUSIVE_LOCK = 2
379
# Constant taken from winerror.py module
380
ERROR_LOCK_VIOLATION = 33
383
LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
384
LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
385
_LockFileEx = ctypes.windll.kernel32.LockFileEx
386
_UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
387
_GetLastError = ctypes.windll.kernel32.GetLastError
389
### Define the OVERLAPPED structure.
390
# http://msdn2.microsoft.com/en-us/library/ms684342.aspx
391
# typedef struct _OVERLAPPED {
392
# ULONG_PTR Internal;
393
# ULONG_PTR InternalHigh;
404
class _inner_struct(ctypes.Structure):
405
_fields_ = [('Offset', ctypes.c_uint), # DWORD
406
('OffsetHigh', ctypes.c_uint), # DWORD
409
class _inner_union(ctypes.Union):
410
_fields_ = [('anon_struct', _inner_struct), # struct
411
('Pointer', ctypes.c_void_p), # PVOID
414
class OVERLAPPED(ctypes.Structure):
415
_fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
416
('InternalHigh', ctypes.c_void_p), # ULONG_PTR
417
('_inner_union', _inner_union),
418
('hEvent', ctypes.c_void_p), # HANDLE
421
class _ctypes_FileLock(_OSLock):
423
def _lock(self, filename, openmode, lockmode):
424
self._open(filename, openmode)
426
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
427
overlapped = OVERLAPPED()
428
result = _LockFileEx(self.hfile, # HANDLE hFile
429
lockmode, # DWORD dwFlags
430
0, # DWORD dwReserved
431
0x7fffffff, # DWORD nNumberOfBytesToLockLow
432
0x00000000, # DWORD nNumberOfBytesToLockHigh
433
ctypes.byref(overlapped), # lpOverlapped
437
last_err = _GetLastError()
438
if last_err in (ERROR_LOCK_VIOLATION,):
439
raise errors.LockContention(filename)
440
raise errors.LockContention(filename,
441
'Unknown locking error: %s' % (last_err,))
444
overlapped = OVERLAPPED()
445
result = _UnlockFileEx(self.hfile, # HANDLE hFile
446
0, # DWORD dwReserved
447
0x7fffffff, # DWORD nNumberOfBytesToLockLow
448
0x00000000, # DWORD nNumberOfBytesToLockHigh
449
ctypes.byref(overlapped), # lpOverlapped
454
last_err = _GetLastError()
455
raise errors.LockContention(self.filename,
456
'Unknown unlocking error: %s' % (last_err,))
459
class _ctypes_ReadLock(_ctypes_FileLock):
460
def __init__(self, filename):
461
super(_ctypes_ReadLock, self).__init__()
462
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
464
def temporary_write_lock(self):
465
"""Try to grab a write lock on the file.
467
On platforms that support it, this will upgrade to a write lock
468
without unlocking the file.
469
Otherwise, this will release the read lock, and try to acquire a
472
:return: A token which can be used to switch back to a read lock.
474
# I can't find a way to upgrade a read lock to a write lock without
475
# unlocking first. So here, we do just that.
478
wlock = _ctypes_WriteLock(self.filename)
479
except errors.LockError:
480
return False, _ctypes_ReadLock(self.filename)
483
class _ctypes_WriteLock(_ctypes_FileLock):
484
def __init__(self, filename):
485
super(_ctypes_WriteLock, self).__init__()
486
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
488
def restore_read_lock(self):
489
"""Restore the original ReadLock."""
490
# For win32 we had to completely let go of the original lock, so we
491
# just unlock and create a new read lock.
493
return _ctypes_ReadLock(self.filename)
496
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
499
if len(_lock_classes) == 0:
500
raise NotImplementedError(
501
"We must have one of fcntl, pywin32, or ctypes available"
502
" to support OS locking."
506
# We default to using the first available lock class.
507
_lock_type, WriteLock, ReadLock = _lock_classes[0]
136
WriteLock = _fcntl_WriteLock
137
ReadLock = _fcntl_ReadLock
142
import win32con, win32file, pywintypes
145
LOCK_SH = 0 # the default
146
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
147
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
149
class _w32c_FileLock(_base_Lock):
150
def _lock(self, filename, openmode, lockmode):
152
self._open(filename, openmode)
153
self.hfile = win32file._get_osfhandle(self.f.fileno())
154
overlapped = pywintypes.OVERLAPPED()
155
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000, overlapped)
164
overlapped = pywintypes.OVERLAPPED()
165
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
172
class _w32c_ReadLock(_w32c_FileLock):
173
def __init__(self, filename):
174
_w32c_FileLock._lock(self, filename, 'rb',
177
class _w32c_WriteLock(_w32c_FileLock):
178
def __init__(self, filename):
179
_w32c_FileLock._lock(self, filename, 'wb',
183
WriteLock = _w32c_WriteLock
184
ReadLock = _w32c_ReadLock
191
# Unfortunately, msvcrt.locking() doesn't distinguish between
192
# read locks and write locks. Also, the way the combinations
193
# work to get non-blocking is not the same, so we
194
# have to write extra special functions here.
197
class _msvc_FileLock(_base_Lock):
207
class _msvc_ReadLock(_msvc_FileLock):
208
def __init__(self, filename):
209
_msvc_lock(self._open(filename, 'rb'), self.LOCK_SH)
212
class _msvc_WriteLock(_msvc_FileLock):
213
def __init__(self, filename):
214
_msvc_lock(self._open(filename, 'wb'), self.LOCK_EX)
217
def _msvc_lock(f, flags):
219
# Unfortunately, msvcrt.LK_RLCK is equivalent to msvcrt.LK_LOCK
220
# according to the comments, LK_RLCK is open the lock for writing.
222
# Unfortunately, msvcrt.locking() also has the side effect that it
223
# will only block for 10 seconds at most, and then it will throw an
224
# exception, this isn't terrible, though.
231
fpos = os.lseek(fn, 0,0)
234
if flags & _msvc_FileLock.LOCK_SH:
235
if flags & _msvc_FileLock.LOCK_NB:
236
lock_mode = msvcrt.LK_NBLCK
238
lock_mode = msvcrt.LK_LOCK
239
elif flags & _msvc_FileLock.LOCK_EX:
240
if flags & _msvc_FileLock.LOCK_NB:
241
lock_mode = msvcrt.LK_NBRLCK
243
lock_mode = msvcrt.LK_RLCK
245
raise ValueError('Invalid lock mode: %r' % flags)
247
msvcrt.locking(fn, lock_mode, -1)
249
os.lseek(fn, fpos, 0)
261
fpos = os.lseek(fn, 0,0)
265
msvcrt.locking(fn, msvcrt.LK_UNLCK, -1)
267
os.lseek(fn, fpos, 0)
272
WriteLock = _msvc_WriteLock
273
ReadLock = _msvc_ReadLock
275
raise NotImplementedError("please write a locking method "
276
"for platform %r" % sys.platform)
added
removed
bzrlib/lock.py
